Which systems have clocks that can go backwards?

This would certainly violate the law of least astonishment! Please tell =
us more about this bug, where the system's clock sometimes can go =
backwards!

-----Original Message-----
From: Tim Bunce [mailto:Tim.Bunce@pobox.com]=20
Sent: Wednesday, June 07, 2006 7:27 AM
To: dbi-announce@perl.org
Cc: dbi-users@perl.org
Subject: ANNOUNCE: DBI 1.51

[much snipped]

Changed DBI::ProfileData to be more forgiving of systems with
unstable clocks (where time may go backwards occasionally).

[rest snipped]

Hopefully helpfully yours,=20
Steve=20
--=20
Steve Tolkin  =A0 Steve . Tolkin at FMR dot COM   508-787-9006
Fidelity Investments   82 Devonshire St. M3L     Boston MA =
02109=20
There is nothing so practical as a good theory.=A0 Comments are by me,=20
not Fidelity Investments, its subsidiaries or affiliates.=20

Re: Which systems have clocks that can go backwards?

Simple. Most system clocks aren't terribly accurate. It's quite easy to
imagine one that runs slightly too fast. Now run e.g. "ntpdate pool.ntp.org"
every so often, and see the clock go back :)

Rhesa (who runs ntpd on all his machines)

Tolkin, Steve wrote:
> This would certainly violate the law of least astonishment! Please tell us more about this bug, where the system's clock sometimes can go backwards!
>
> -----Original Message-----
> From: Tim Bunce [mailto:Tim.Bunce@pobox.com]
> Sent: Wednesday, June 07, 2006 7:27 AM
> To: dbi-announce@perl.org
> Cc: dbi-users@perl.org
> Subject: ANNOUNCE: DBI 1.51
>
> [much snipped]
>
> Changed DBI::ProfileData to be more forgiving of systems with
> unstable clocks (where time may go backwards occasionally).
>
> [rest snipped]
>
> Hopefully helpfully yours,
> Steve

Re: Which systems have clocks that can go backwards?

Rhesa Rozendaal wrote:
> Simple. Most system clocks aren't terribly accurate. It's quite easy to
> imagine one that runs slightly too fast. Now run e.g. "ntpdate
> pool.ntp.org" every so often, and see the clock go back :)
>
> Rhesa (who runs ntpd on all his machines)
>
> Tolkin, Steve wrote:
>> This would certainly violate the law of least astonishment! Please
>> tell us more about this bug, where the system's clock sometimes can go
>> backwards!
>>

FYI: Take a look at the Time::HiRes XS code for Win32 platforms;
you'll be either chagrined or humored by the amount of code
required to get an accurate subsecond timer.

- Dean